I’ve got a USBeeSX (www.usbee.com) as well as the Open Workbench logic sniffer (which now Sparkfun also carries.) The software still has a way to go IMHO and the initial firmware revs of the Open Workbench were a bit flakey so I wouldn’t recommend it for the faint of heart. The obvious big plus however is the 200Msps and 100mhz captures at 16channels… though there are other really good pros for it (including other great capture features and multi-platform use.) They are supposedly looking at doing a digital scope add-on for it in the future as well so I’m not done with it by any means
The USBeeSX caps at 24Msps and can have some capture timing issues on a slower PC (at least it did when I was researching it quite a few sw revs ago), however I find the Windows software works really well. It saved my butt a few months back when a spec sheet from some hardware I got from over-seas said it used SPI, but found it it was only “SPI-like”, LOL. Also helped out a few times isolating I2C issues. I find I use this rather than the OWB board just because I plug it in and it just works and the software works well.
I was torn between the Saleae (my friend has one and raves about it), but I ended up liking the USBee a bit better for some of the protocol add-ons for it that were better at the time. I ended up upgrading to the Pro version of the Software with a coupon code, and like the ability to use the PacketPresenter definitions.
Just my .02.